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SYNOPSISMicroporous hydrophobic polypropylene (PP) membranes (Celgard@ 2400 and 2500) were modified by the chemical modification technique to impart permanent hydrophilicity. The modification was carried out in two stages. In the first stage, the membranes were hydroxylated by treatment with aqueous potassium peroxydisulfate solution under a strong flow of nitrogen. In the second stage, the hydroxylated membranes were subjected to grafting of acrylamide using cerric ammonium nitrate as an initiator. Subsequently, acrylamide grafted PP membranes were partially hydrolyzed to have carboxyl functional groups at the membrane surfaces. Under given experimental conditions the grafting also took place within the pores of the microporous structure of hydrophobic PP Celgard@ membranes. Modified membranes exhibited permanently wettable characteristics by aqueous solutions and appeared translucent when immersed in water. Contact angle measurements showed excellent wetting properties with water. In contrast to unmodified Celgard@ membrane, the modified membranes exhibit water permeability even after repeated drying.

Arylene ether multiblock copolymers of the (AB)n‐type with various degrees of sulfonation have been prepared by a two‐step polycondensation procedure. Multiblock copolymers in high yields and of high molecular weights were obtained. For comparison random copolymers with the same overall composition were synthesized. The theoretical ion‐exchange capacities (IEC) of the materials were ranging from 0.50 mmol/g to 1.25 mmol/g. The water‐uptake of the multiblock copolymers showed a linear dependency from the IEC and was increasing with increasing IEC. No differences were observed between random and block copolymers. Furthermore, the hydrolytic stability of aromatic sulfonic acid groups was investigated in this study. Aromatic sulfonic acids, having additional electron donating groups, especially in ortho‐ or para‐position to the sulfonic acid group are sensitive to hydrolytic desulfonation. On the other hand electron‐withdrawing groups in meta‐position showed a stabilizing effect.

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